"The selected item could not be opened. If you purchased this item from Amazon, delete this item and redownload it from Archived Items available in Home."

I keep getting this error! Initially I thought I haven't convert properly with Calibre so I went back to reconvert to .mobi and reuploaded via Calibre to my K3. Still didn't work, so I tried another. I converted it to .azw3 and reuploaded via Calibre to my K3. Still didn't work!

Can you view the book in Calibre? If so then it could be a number of things from a corrupted source to a missing font. I would use the mobi-unpack plugin to examine the innards of the book. You can always reimport the html from it and convert from that instead.